Analysis of the Gs/mitogen-activated protein kinase pathway in mutant 549 cells

Heterotrimeric G protein-coupled receptors can activate the mitogen-activated protein kinase (MAPK) cascade. Recent studies using pharmacological inhibitors or dominant-negative mutants of signaling molecules have advanced our understanding of the pathways from G protein-coupled receptors to MAPK. However, molecular genetic analysis of these pathways is inadequate in mammalian cells. Here, using the well characterized G,cu-and protein kinase A-deficient S49 mouse lymphoma cells, we provide the molecular genetic evidence that G(s) alpha is responsible for transducing the beta-adrenergic receptor signal to MAPK in a protein kinase A-dependent pathway involving Rap1 and Raf (but not Ras) molecules.